Hydraulic lifting device for lifting heavy loads

ABSTRACT

A hydraulic lifting device for lifting heavy loads, especially by steps, in which two vertically spaced adjusting nuts are arranged on and in meshing engagement with a vertical spindle which is surrounded by an annular cylinder-piston system, the elements of which are relatively movable to each other to perform a major stroke only when at least one of said nuts is being rotated, rotation of either one of the nuts resulting in an axial movement of the spindle.

United States Patent [1 1 Jan. 1, 1974 Lietzke 3,278,158 10/1966 Saldana254/106 [75] Inventor: Hemz Lietzke Neuss Germ-any PrimaryExaminer-Othell M. Simpson [73] Assignee: Schiess Aktiengesellschaft,Attorney-Walter Becker DusseIdorf-Oberkassel, Germany [22] Filed: Mar.1, 1972 [21] Appl. No.2 230,779 57 ABSTRACT [30] Foreign ApplicationPriority Data A hydraulic lifting device for lifting heavy loads, espe-Mar. 9, 1971 Germany P 21 11 244 7 cially by steps, in which twovertically spaced adjusting nuts are arranged on and in meshingengagement [52] US. Cl. 254/106 with a vertical spindle which issurrounded by an an- [51] Im. Cl B66f 1/00, E02d 21/00 l r y n r-p n ym. h m n f which [58] Field ofSearch 254/l05-108, 89 H, 93 R; arerelatively movable to each other to perform a 74/1[1; 61/465 majorstroke only when at least one of said nuts is being rotated, rotation ofeither one of the nuts result- [56] References Cit d ing in an axialmovement of the spindle.

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WW Hm l mh In Inn 5 TI 4 v9 {I1 5/4 .10 mm N WIII 2 7 W L 1 M 2HYDRAULIC LIFTING DEVICE FOR LIFTING HEAVY LOADS The present inventionrelates to a hydraulic lifting device for lifing heavy loads, especiallyfor step-wise lifting as it occurs, for instance, in the buildingindustry, in order to lower bridges onto their bearings, or in order tolift prefabricated ceilings to the respective height, or for liftingheavy forms for pouring cement, and the like. With operations of thistype, lifting devices are required which will be able to lift up to1,000 tODS.

It is known for lifting or lowering operations to employ assemblywinches which, however, become uneconomical when loads are involved thatare in excess of 200 tons. Moreover, the employment of such assemblywinches are limited by their dimensions. If, for instance, prefabricatedceilings have to be lifted which after being lifted to their requiredheight have to be suspended at a plurality of points on concrete columnsor walls, it is necessary in conformity with the number of the intendedsupporting points to employ a greater number of lifting devices whichwill assure a lifting operation with equal strokes, since otherwise, adeformation and a breaking of the prefabricated ceiling may beencountered. By means of cable winches, a uniform stroke of a pluralityof lifting devices cannot be realized because the cables can stretchdifferently, for instance, already due to the fact that the cables canwind at different diameter and when resting on cable windings therebelowcan slide between said last mentioned windings and thus can yield.

In addition to assembly winches, also devices with lifting cylinders forinstance hydraulic lifts for pressing and the like are employed whichyield higher lifting forces then cable winches. The heretofore knownlifting devices of this type are, however, limited as to theiremployment because they permit only relatively short lifting strokes.The employment of these last mentioned devices therefore requires acontinuous resetting while each resetting operation prior to the liftingoperation requires a certain lowering of the load to be lifted, in orderfrom the very start to assure contact with the load to be lifted. Also,with these devices when simultaneously employing a plurality of suchdevices it cannot be assured that the lifting stroke of all devices willbe the same. Disuniformities will occur in particular in connection withthe resetting operation when a multiple of that lifting height isrequired which the device can perform per one stroke.

It is, therefore, an object of the present invention to provide ahydraulic lifting device for lifting heavy loads, especially forstepwise lifting, which will have relatively small dimensions and willmake it possible to multiply the maximum stroke thereof in steps whilemeans are provided which will safeguard the respective obtained level ofthe load and when simultaneously employing a plurality of liftingdevices will permit a checking and equalization of the lifting stroke ofall lifting devices in order in this way to assure an equalization ofthe lifting stroke of all devices.

These and other objects and advantages of the invention will appear moreclearly from the following specification, in connection with theaccompanying drawing, in which:

FIG. 1 is a section through a hydraulic lifting device according to theinvention, while said device is in use.

FIG. 2 represents a section taken along the line II-II of FIG. I, moreclearly showing the drive for the adjusting nut.

The hydraulic lifting device according to the present invention ischaracterized primarily in that on a vertically arranged threadedspindle on the lower end of which the load may be suspended, or on theupper end of which the load may be rested, there are arranged twoadjusting nuts in spaced relationship to each other. The lower one ofthese two adjusting nuts is adapted to rest on a stationary mounting orbearing and also an annular hydraulic cylinder is adapted to rest onsaid mounting or counter-bearing, which cylinder, with play, from aboveextends over the adjusting nut and above the lower adjusting nut extendswith play around the spindle. Pressure fluid conveying conduits leadinto said annular hydraulic cylinder at the upper and lower end througha reversible valve, said conduits being connected to a source ofpressure. An annular piston extends from above into said cylinder whileextending below and above the upper adjusting nut with play.

In this way, a hydraulic lifting device for lifting and lowering ofheavy loads has been created which permits the following operation: Thelifting devices is first, by means of the annular hydraulic cylinderrested on a stationary counterbearing which may be located, forinstance, above the lower end of the spindle and to which the load to belifted is suspended. Subsequently, both adjusting nuts are turned on thethreaded spindle so that they are displaced in upward direction. Thisdisplacement will be ended when the lower adjusting nut abuts theannular hydraulic cylinder thereabove and the upper adjusting nut abutsthe annular cylinder thereabove. Thereupon, the annular piston is movedout of the annular hydraulic cylinder while the annular piston engagesthe upper adjusting nut from below and through the latter moves thespindle with the load in upward direction. Simultaneously, the loweradjusting nut is so rotated that it, itself, remains at the givenheight, but at the same time permits the upward displacement of thethreaded spindle with the load. The speed of the adjusting nutcorresponds to the speed at which the piston carries out its stroke.Thus, the number of the revolutions of the adjusting nut indicates thelifting stroke which may be within the maximum stroke of the piston.When the intended lifting height has been reached, the lower adjustingnut is stopped whereby also a further displacement of the annular pistonand thus a further lifting of the spindle with the load is not longerpossible. If now the inner chamber of the cylinder is vented, the entireunit will rest on the lower adjusting nut and through the latter on thecounterbearing or support. Thereupon, the annular piston is moved intothe annular hydraulic cylinder while at the same time the upperadjusting nut is rotated so thatit will again approach the loweradjusting nut until its starting position has been reached. In thisconnection, the spindle with the load remains at the previously reachedlevel. An upward movement of the spindle with the load is impossible andthe operation can be repeated in the same manner in order again to liftthe spindle with the load by a predetermined distance.

When simultaneously employing a plurality of lifting devices, a hundredpercent synchronism of all lifting devices can be realized by each timetemporarily ex eluding that lifing device from the hydraulic circuit inwhich the lower adjusting nut has carried out a full revolution. Thelower nut is again included in the hydraulic circuit as soon as allother lifting devices have completed the same lifting stroke. Inasmuchas the lifting operation of all lifting devices is dependent on thateach time after a revolution of the lower adjusting nut a check iseffected in such a way that with all lifting devices the correspondingrotation of the adjusting nut was carried out, the danger is eliminatedthat one of the lifting devices may at a faster rate than the otherreach its end value. The above mentioned control may be realized byhaving the adjusting nut cooperate with limit switches by means of whichthe flow of the hydraulic fluid into the annular hydraulic cylinder iscontrolled.

The last mentioned possibility presents itself particularly when inconformity with the invention the two threaded nuts are adapted to bemotor driven individually, or in common, so that by means of the motorsit is possible precisely to adapt the supply and withdrawal of hydraulicfluid to the annular hydraulic cylinder and also to carry out thecontrol by means of limit switches.

According to a further development of the invention, it may be providedthat each of the two adjusting nuts is equipped with a gear ring and canbe driven by means of a circulating chain.

According to a further feature of the invention, the motor which isassociated with the lower adjusting nut may be arranged on the annularhydraulic cylinder while the motor which is associated with the upperadjusting nut may be connected to the annular piston. Both motors may beadapted to be coupled to each other when the annular piston has movedinwardly. A coupling may, for instance, be effected when the spindlewhile not being under load is to be longitudinally displaced in order tobring the same to their starting position without being under load, forwhich purpose it is thus necessary to displace the annular piston.

Instead, as described above, to suspend the load on the lower end of thethreaded spindle, it is also possible to support the load upon the upperspindle end. In this connection, the working method is the same asdescribed above.

Also, the lowering of a load is possible which was preceded by theoutward movement of the annular piston. During the lowering of the loadthe spindle rests upon the upper adjusting nut, while simultaneously inconformity with the displacement of the annular piston into the annularhydraulic cylinder, the lower adjusting nut is turned without load andthus moves in conformity with the stroke on the spindle onto the upperadjusting nut.

Referring now to the drawing in detail, it will be seen from FIG. I thatthe illustrated lifting device comprises a threaded spindle 1 on whichare arranged in spaced relationship to each other an upper adjusting nut2 and a lower adjusting nut 3. In the specific position shown in thedrawing, the lower surface of the lower adjusting nut 3 rests directlyon the support 4 in which instance, for example, a part of a column orwall may be involved during the lifting of a ceiling. With the specificexample referred to, it may also be assumed that a prefabricated ceilingis suspended onto the lower end of spindle l. The lifting of saidceiling is'to be effected by means of a plurality of devices which aredistributed around the ceiling plate in order thus to assure a uniformlifting. However, it is also possible to rest the load to be lifted onthe upper end of the spindle 1.

The annular hydraulic cylinder 5 extends around the lower adjusting nut3 while said hydraulic cylinder 5 at the same time extends with playover the lower adjusting nut 3 and in addition thereto also extendsabove the adjusting nut 3 with play around the spindle 1. The cylinderportion which extends around the spindle 1 is designated with thereference numeral 6. Between the cylinder portion 6 and the outerannular cylinder mantle 7 there is located a cylinder chamber 8, intowhich the annular piston 9 extends from above. Piston 9 sealinglyengages by means of its piston ring 10 the outer mantle 7 of the annularhydraulic cylinder 5 and by means of its piston ring 11 sealinglyengages the cylinder portion 6. The annular piston 9 extends with playaround the spindle 1 below the adjusting nut 2. Furthermore, the annularpiston 9 also engages the adjusting nut 2 from below and extends abovethe adjusting nut 2 near to the spindle 1 while leaving an annular playbetween spindle 1 and the adjacent portion of piston 9. A driving motor12 adapted to be hydraulically actuated is fastened to the cantilever 13of the annular piston 9. A chain sprocket 14 is provided on the drivingshaft 19 which extends parallel to the axis of the spindle 1. Chain 15extends around the sprocket 14 and meshes with the chain gear ring 16 onthe adjusting nut 2. Connected to the cantilever 17 of the hydraulicannular cylinder 5 is a hydraulic driving motor 18, the drivng shaft 19'of which, has keyed thereto the chain sprocket 14 around which a chain21 passes, which chain meshes with the chain gear ring 16 on the loweradjusting nut 3. The other end of the driving shaft 19' which protrudeson the other side of the motor 18 may, by means of the clutch 20, becoupled to shaft 19 of motor 12. Such coupling will be possible when theannular piston 9 has moved into the hydraulic annular cylinder 5, asshown in FIG. 1. Such coupling may be effected when it is desired thatthe spindle 1 be longitudinally displaced while being under no load.Such longitudinal displacement is brought about by driving the adjustingnuts 2 and 3 in the same direction of rotation and at the same speed.The drive of the adjusting nuts 2 and 3 by means of the chains 15 and 16is shown in FIG. 1, while FIG. 2 more particularly illustrates the driveof the adjusting nut 2 by the chain 15. FIG. 1 also illustrates indetail the hydraulic control of the lifting device in combination withthe hydraulic control of the driving motors l2 and 18 for the adjustingnuts 2 and 3, respectively. This control will be explained further belowin connection with the description of the operation of the deviceaccording to the invention.

It may be assumed that the spindle l, the annular piston 9 and theannular hydraulic cylinder 5 occupy their respective position relativeto the support 4 as shown and it may furthermore be assumed that theload to be lifted is suspended at the lower end of the spindle 1. Inthis starting position, the adjusting nut 3 has its lower surfaceresting on the support 4 and a similar situation prevails with the lowersurface of the annular hydraulic cylinder 5. If now, fluid underpressure is pressed through the conduit 23 and inlet opening 22 into thecylinder chamber 8' below the annular piston 9, the pressure medium willmove the annular piston 9 out of the hydraulic cylinder 5. This outwardmovement is first possible only to the extent of the play 24 between theupper surface of the adjusting nut 3 and the associated surface of theannular hydraulic cylinder 5. Inasmuch as during the outward movement ofthe annular piston 9, the adjusting nut 2 and thus also the spindle 1are moved along with the piston 9, a further outward movement requiresthat the adjusting nut 3 is displaced along the spindle 1 relative tothe outward movement of the spindle. This displacement is effected inview of the fact that by means of the motor 18 through the interventionof the chain 21 the adjusting nut 3 is rotated in the sense of adownward movement. In conformity with the distance or stroke of thedisplacement of the adjusting nut 3, it is thus possible that theannular piston 9 moves upwardly and can take along the spindle 1 andthereby the load to be lifted. If it is assumed that the load is liftedby a plurality of devices according to FIG. 1, it is possible by meansof limit switches on motor 18 to bring about that the motor 18respectively is stopped and will standstill each time after a revolutionof the lower adjusting nut 3 and will start moving again only when themotors 18 of all lifting devices have rotated the lower adjusting nut 3once. In this way, it will be assured that the individual liftingstrokes of all lifting devices will be equal and the maximum liftingstroke of a lifting operation can correspond to the total stroke of theannular piston 9.

For purposes of carrying out a lifting action by a stroke which exceedsthe maximum outward stroke of the annular piston 9, a following up ofthe device is effected in the following manner. After the annular piston9 has moved out of the annular hydraulic cylinder 5 by its maximumstroke while the lower adjusting nut 3 was correspondingly turned fordisplacement on spindle 1, a slight further displacement of the loweradjusting nut 3 is effected in such a way that the last mentioned nutwill have its lower surface in engagement with the support orcounterbearing 4. Thus, the spindle 1 and the load are no longersupported by or rested on the annular piston 9, but instead throughadjusting nut 3 rests directly on the support 4. Thereupon, the annularpiston 9 is moved into the annular hydraulic cylinder 5 while thepressure medium escaps from the annular hydraulic cylinder 5 through theopening 22 and the conduit 23. This escape can be aided by introducingpressure fluid through inlet 26 in the hydraulic cylinder 5 throughconduit 25. The displacement of the annular piston 9 into the annularhydraulic cylinder 5 requires that simultaneously the upper adjustingnut 2 is turned in such a way that it is correspondingly displaceddownwardly on spindle 1. To this end the sprocket wheel 14 is driven bymotor 12 so that the adjusting nut 2 will, by means of chain 15, beturned correspondingly. When the annular piston 9 has moved completelyinwardly, a new outward movement of the annular hydraulic cylinder ispossible while the spindle l is again taken along and thus also theload. To this end the above mentioned steps for lifting are initiated.

The operation is effected in a corresponding manner when the load restsfrom above on the spindle.

The starting position of spindle 1 can be set while the annular piston 9is in its inward position, by turning the adjusting nuts 2 and 3 insynchronism by means of motors 12 and 18 so that exclusively the spindle1 will be longitudinally displaced in one or the other direction. Inorder to assure the said synchronism, the two shafts l9 and 19' of themotors 12 and 18 can be coupled by means of the coupling 20.

FIG. 1 also diagrammatically shows the hydraulic control of the annularpiston 9 and the hydraulic control of the driving motors 12 and I8.

The hydraulic medium is selectively, by means of the pressure pump 27via control valve 28 pressed through conduits 23 and into the cylinderchamber 8 depending on whether the annular piston 9 is to be movedoutwardly or inwardly. The pressure relief valve 29 will see to it thatthe supply of the pressure medium into the cylinder chamber 8 will bestopped when the annular piston 9 is, due to its abutment against one orthe other adjusting nut 2, 3 prevented from being further displaced sothat the stroke is determined by the respective speed of the adjustingnut 2 or 3 in conformity with the direction of the stroke. The controlof the drive motors 12 and 18 is effected hydraulically through theintervention of the pressure pump 31 with following relief valve 32. Anelectrohydraulic control valve determines the direction of rotation ofthe hydromotors l2 and 18. Additionally there may be provided limitswitches, the pulses of which actuate the control valve 30. By means ofthis control it is made possible that when employing a plurality oflifting devices, individual strokes can be effected which, for instance,correspond to one revolution of a spindle nut 2 or 3 so that a totalnumber of lifting steps can be carried out in one working operationwhich total number corresponds to the total stroke or any desiredpartial stroke of the annular piston 9.

It is, of course, to be understood that the present invention is, by nomeans, limited to the particular showing in the drawing, but alsocomprises any modifications within the scope of the appended claims.

What I claim is:

1. A hydraulic lifting device for lifting heavy loads, especially forlifting such loads in steps, which includes: a vertically movablethreaded spindle, two adjusting nuts respectively arranged on saidspindle in spaced relationship to each other and in meshing engagementwith said spindle, stationary supporting means, the lower one of saidtwo adjusting nuts being adapted to engage and rest on said supportingmeans, an annular hydraulic cylinder surrounding said spindle with playand also with play extending around said lower nut and adapted to reston and be supported by said supporting means, an annular reciprocabledouble acting piston having a first section reciprocably mounted in saidannular cylinder and also having a second section surrounding saidspindle with play and extending with play above and below said uppernut, said annular cylinder within the range of its longitudinalextension being provided with fluid inlet and outlet means for selectivecommunication with a fluid pressure source and with a fluid reservoir,and actuating means respectively drivingly connectable to said first andsecond nut for engaging the same in either direction to therebyselctively move said spindle uwardly and downwardly.

2. A device according to claim 1, which includes motor means for drivingeach of said nuts independently of the other.

3. A device according to claim 1, which includes driving means common tosaid nuts for driving the same.

4. A device according to claim 1, in which each of said adjusting nutsis provided with circumferential teeth adapted to mesh with and to bedriven by means .of a chain.

5. A device according to claim 4, which includes a first motorassociated with said cylinder and equipped with a first sprocket wheel,and also includes a second that one of said two motors is connected tosaid cylinder.

7. A device according to claim 6, which includes clutch meansrespectively associated with said first and second motors for drivinglyinterconnecting said motors when said piston occupies its substantiallyinnermost position in said cylinder.

1. A hydraulic lifting device for lifting heavy loads, especially forlifting such loads in steps, which includes: a vertically movablethreaded spindle, two adjusting nuts respectively arranged on saidspindle in spaced relationship to each other and in meshing engagementwith said spindle, stationary supporting means, the lower one of saidtwo adjusting nuts being adapted to engage and rest on said supportingmeans, an annular hydraulic cylinder surrounding said spindle with playand also with play extending around said lower nut and adapted to reston and be supported by said supporting means, an annular reciprocabledouble acting piston having a first section reciprocably mounted in saidannular cylinder and also having a second section surrounding saidspindle with play and extending with play above and below said uppernut, said annular cylinder within the range of its longitudinalextension being provided with fluid inlet and outlet means for selectivecommunication with a fluid pressure source and with a fluid reservoir,and actuating means respectively drivingly connectable to said first andsecond nut for engaging the same in either direction to therebyselctively move said spindle upwardly and downwardly.
 2. A deviceaccording to claim 1, which includes motor means for driving each ofsaid nuts independently of the other.
 3. A device according to claim 1,which includes driving means common to said nuts for driving the same.4. A device according to claim 1, in which each of said adjusting nutsis provided with circumferential teeth adapted to mesh with and to bedriven by means of a chain.
 5. A device according to claim 4, whichincludes a first motor associated with said cylinder and equipped with afirst sprocket wheel, and also includes a second motor associated withsaid piston and equipped with a second sprocket wheel, and first andsecond chain means respectively drivingly connecting said first andsecond sprocket wheels with the respective circumferential teeth oftheir respective adjacent adjusting nuts for driving same.
 6. A deviceaccording to claim 5, in which each of said first and second motors is ahydraulic motor, and that one of said two motors is connected to saidcylinder.
 7. A device according to claim 6, which includes clutch meansrespectively associated with said first and second motors for drivinglyinterconnecting said motors when said piston occupies its substantiallyinnermost position in said cylinder.